Private plane under too much stress in crash, investigators say

A popular 68-year-old veterinarian may have pushed his homebuilt plane beyond its limits just before it crashed in Calaveras County a year ago, federal investigators have concluded.

With clinical phrasing that masks some life-and-death details, the National Transportation Safety Board cited “the pilot’s excessive flight control inputs” as contributing to the airplane falling apart in flight. Those “inputs,” investigators said, “led to flight that exceeded the structural limits of the airplane and resulted in structural failure of both wings.”

The safety board’s “probable cause” conclusion quietly released last month ends the formal inquiry into the Nov. 23, 2012, crash that killed Dr. Russell Hackler. It was one of 22 fatal airplane crashes in California last year, most of which remain under investigation.

“It doesn’t change the outcome,” Hackler’s widow, Kathie Hackler, said in a telephone interview Tuesday, “but it’s a way of finding closure, rather than waiting forever.”

A resident of Danville, Kathie Hackler said she last heard from safety board officials during the summer when the investigation was still underway. A reporter’s phone call Tuesday was the first she learned that the investigation into her husband’s death had been officially concluded, though she said the conclusions themselves did not surprise her.

“I mean, you always hope it wasn’t pilot’s error,” Kathie Hackler said, “but my understanding is that in a very high percentage of these accidents, they find the pilot did something (wrong.) That is the usual outcome.”

The investigation into the crash near Calaveras County-Maury Rasmussen Field Airport moved more quickly than many.

On May 18, 2011, for instance, a single-engine experimental airplane bound for Tracy crashed near Bear River Reservoir in mountainous Amador County. The crash killed the pilot, well-known San Joaquin Valley winemaker and entrepreneur Robert “Budge” Brown. Thirty months later, the search to determine the probable cause of the crash continues.

Similarly, the investigation into a May 22, 2009, crash that killed veteran Navy aviator Lt. Cmdr. Luther H. Hook III and his three daughters, who lived in Clovis, Calif., was not concluded until March 2012.

Investigations into fatal aircraft crashes typically take between 18 months and two years, safety board officials say. Factual reports come first for agency officials, who every year investigate an average of about 2,000 aviation accidents and about 500 other kinds of accidents annually.

Last June, the safety board’s investigator-in-charge, Thomas Little, released a five-page factual report summarizing what was known about the accident that killed Hackler. Little is based in the safety board’s Western Pacific Regional Office in Federal Way, Wash.

The report details Hackler’s aviation background, such as the 5,138 hours of flight time he had accumulated. It illuminates the plane, a two-seat, single-engine craft, capable of landing on both land and water, called a Sater Coot A-Amphibian. It describes, minutely, the debris that was scattered across the accident site about 1.25 miles south of the airport’s runway.

“It’s good to know as much as you possibly can,” Kathie Hackler said.

The initial report also includes statements from several unidentified witnesses, one of whom reported seeing Hackler’s plane traveling fast and in a steep bank immediately prior to it going into a spin.

“The witness added that after the first revolution of the spin he observed the leading edge come off of a wing,” the report stated. “After the second revolution and approaching a third, it appeared as if the other wing had separated. The airplane then went out of view.”

In the final report, investigators noted “there were no obvious signs of rot or pre-existing conditions in the wood spars examined, and none of the wing attachment bolts failed.” That led to the conclusion that “the pilot’s control inputs stressed the airplane’s wings beyond their design capabilities.”

Kathie Hackler offered her own coda: "As for what caused Russ to have to use the controls so vigorously, we will never know. Those what-if’s will always remain."